What is the useful economic life of a diesel inboard?

rbw156 · 18 August 2007, 05:47

What is the useful economic life of a diesel inboard? Assuming it has been well maintained. When would it need a strip down and rebuild? Are we talking 5,000 hours or 50,000 hours?

peterb · 18 August 2007, 07:18

I doubt 50,000 hours - but I would guess that its probably at least 10,000 hours.

If you ignore the "marinising" stuff, and refer to the actual engine then really you can draw comparisons of sorts with modern tractor diesel engines and also modern car diesels.

My neighbour is a town taxi driver - presently he has clocked up 400k miles on his diesel car. At an average of 30mph (optimistic?), thats 13,000 hours. Theres not much wrong with the engine - although the rest of the car is wrecked!

If you look on a Tractor Sales site - you will see endless tractors with 10,000 hours on them. Still classed as decent bits of kit and making good money.

I appreciate that the car and tractor engines are probably less "stressed" in terms of power output than their marine counterparts. My marine diesel produces 260hp from 3.7 litres - and there are proposals to take 300hp from the same block.

However, unless you are a complete idiot, you dont run your engine flat out all the time, so this may not be a huge factor in longevity.

Lastly - just to say - a diesel engine of any sort will only give this sort of lifetime if the oil/filters are changed exactly as per manufacturers standards. Old oil = shortened life..........

jwalker · 18 August 2007, 11:37

Quote:

Originally Posted by peterb

... a diesel engine of any sort will only give this sort of lifetime if the oil/filters are changed exactly as per manufacturers standards.

Or sooner.

Searider · 18 August 2007, 12:51

They don't usually wear out - ancilliaries tend to corrode causing problems.

Coolers gradually furr up and if not dealt with can lead to overheating and possible death of the engine.

Age and preventative maintainance rather than hours determine life.

codprawn · 18 August 2007, 13:28

As peterb says it's how you use it - it's revs that kill a diesel - if you look at the ratings for marine diesels you will see commercial use engines are derated by as much as 50 - 60%!!! Basically this is just a rev limiter - typically dropping the revs from say 2400rpm - 1800rpm.

The longest life diesels are the old plodders - the slow running diesels like Kelvin and Gardner etc - they WILL go on for ever. Modern high speed diesels don't have such an easy life.

A lot also depends on what they are attached to. A water jet is very easy on an engine - the revs tend to stay constant and there are no sudden shock loads.

Lightweight marine diesels are usually adopted car engines and tend to run at quite high speeds for a diesel - whilst they will last a reasonable time they won't still be chugging around in 20 years time unless they are really treated gently - and would you want to do that on a RIB???

GuyP · 18 August 2007, 14:09

Quote:

Originally Posted by codprawn

The longest life diesels are the old plodders - the slow running diesels like Kelvin and Gardner etc - they WILL go on for ever.

My uncle has an early 1960's Brit diesel as a bass fishing engine in his Mitchel 23. A real arse to start but once it's up it'll go on forever. I'm amazed it still runs but i guess it's so simple (single cylinder i think - you can actually hear every revolution at low revs) that it's never going to die.

codprawn · 18 August 2007, 14:30

I suspect it's a Lister - as used in many generators etc. As you say a bitch to start but keep going forever.

You often see old Lister gennys for sale at about £600 - for the same money you can have a nice shiny chinese generator brand new. Many people make the mistake of buying the new one and yet the old Lister will still be around in another 40 years. Mates of mine are from the Gambia and they soon realised that buying a new chinese generator is a false economy!!